1. Field of the Invention
The present invention relates generally to a transmission method and a network system. More particularly, the invention relates to a transmission method and a network system for accommodating a plurality of kinds of traffic (STM, ATM, IP, and so forth) in a common network.
2. Description of the Related Art
Conventional networks have been constructed with using a circuit switched network centered at a voice telephone network and private line as a center thereof. However, in recent years, associating with quick growth of internet, networks using an IP (internet protocol) are abruptly growing. Also, in the sound circuit, the increase of traffic using modems stresses a use condition of circuit switching system.
On the other hand, as modes of circuit switching, there are Synchronous Transfer Mode (STM), Asynchronous Transfer Mode (ATM) and Internet Protocol (IP) establishing respectively independent networks. For example, IP data is transferred to an IP network established by routers and private lines after a circuit switching process, and an ATM network is established as the system considering data transfer. The transmission system is sped up by Synchronous Optical Network/Synchronous Digital Hierarchy SONET/SDH) and is increased in capacity by introduction of Dense Wavelength Division Multiplexing (DWDM).
However, as a result that operation of establishing the independent networks with a complicated compromise of various factors, establishment, operation and maintenance of the networks becomes complicated. Accordingly, for solving such problems, it is inherent to accommodate STM, ATM and IP in a single network.